A primary objective of most fiber optic connectors is to optically interconnect the optical fibers upon which the fiber optic connector is mounted with other optical fibers or other optical components in a manner which minimizes the attenuation of the optical signals while maintaining direct fiber contact. As the applications for optical communications demand increased levels of performance and, therefore, decreased levels of attenuation, more demands are being placed upon fiber optic connectors to provide a secure optical connection with even lower levels of attenuation and to continue to provide direct fiber contact as the connector is subjected to increased physical loads or forces.
In many applications, a fiber optic connector that is mounted upon the end portions of one or more optical fibers is inserted into a passageway defined by an adapter, such as a sleeve having a generally rectangular cross-section. By inserting another fiber optic connector into the opposite end of the adapter, the fiber optic connectors and, in turn, the optical fibers upon which the fiber optic connectors are mounted can be mated. Alternatively, the adapter can be part of an optical or optoelectronic module for aligning the optical fibers upon which the fiber optic connector is mounted with other optical fibers or other optical components within the module.
Unfortunately, a fiber optic connector and/or the optical fibers upon which the fiber optic connector is mounted are often subject to side pull forces following the insertion of the fiber optic connector into an adapter. Among other effects, these side pull forces can prevent direct fiber contact and can increase the attenuation introduced by the fiber optic connector. As described below, this decreased fiber contact and increased attenuation is believed to be due to insufficient clearance between the various components of the fiber optic connector and the adapter.
A conventional multifiber connector includes a connector housing or plug, a ferrule such as an MT ferrule mounted upon the end portions of a plurality of optical fibers, a pin clamp, a spring and a spring push. Typically, the ferrule is positioned within a lengthwise extending passageway defined by the connector housing such that the shoulder of the ferrule engages a corresponding shoulder of the connector housing that projects into the passageway proximate the forward end of the connector housing. The pin clamp and spring are also disposed within the passageway defined by the connector housing to the rear of the ferrule. As such, the pin clamp can engage guide pins that extend through corresponding bores defined by the ferrule. In addition, the spring push can be at least partially inserted into the rear end of the passageway defined by the connector housing such that the spring which is compressed between the spring push and the pin clamp exerts a forwardly-directed force upon the pin clamp and the ferrule such that the forward end of the ferrule is extended beyond the forward end of the connector housing.
Once the fiber optic connector 10 has been inserted into an adapter 11 and side pull forces f.sub.0 are applied, the connector housing 14 will generally rotate through an angle .theta..sub.p relative to the adapter and, more particularly, relative to a longitudinal axis L defined by the passageway defined by the adapter. This rotation of the connector housing will generally continue until the connector housing contacts the inner sidewalls of the adapter as shown in FIG. 1. As also shown in FIG. 1 following rotation of the fiber optic connector relative to the adapter, the connector housing contacts the ferrule 16 and/or the pin clamp 18 as the connector rotates in response to the side pull forces f.sub.0 so as to cause the ferrule and the pin clamp to also rotate with the connector housing through an angle .theta..sub.f relative to the longitudinal axis L defined by the adapter. As a result of this rotation of the ferrule, the alignment of the optical fibers upon which the ferrule is mounted will be significantly impaired, thereby preventing direct fiber contact and attenuating the optical signals to a greater degree. As will be apparent, the rotation of the ferrule and, in turn, the attenuation of the optical signals is particularly significant in instances in which single mode optical signals are being transmitted, in instances in which the ferrule is mated with another ferrule that is designed to be fixed in place, i.e., a fixed ferrule, and in instances in which the connector housing is somewhat undersized for the respective adapter so as to permit the connector housing to rotate through a relatively large angle .theta..sub.p with respect to the longitudinal axis L defined by the adapter.